Human categories are organized into different kinds, for example, living and nonliving things, animates and inanimates, objects and substances. These differences are evident in how people reason about different kinds and in their neural organization of categories. This research investigates the developmental origins of these distinctions. The studies test the hypothesis that the organization of categories into different kinds is the learned consequence of correlations among the perceptual properties of things, lexical category structure, and language. To test this hypothesis the research proposes 11 studies investigating the statistical regularities presented by the first 300 nouns that children learn. The regularities in category structure, their relation to perceptual cues, to events, and to the verbs with they co-occur will be studied in two languages -- English and Japanese. By comparing the structures presented by two languages we can tease apart the relevant contributions of language and perceptual correlations. We model the processes through which these regularities may organize categories into kinds with neural networks. From these neural network simulations, we derive predictions that are then tested in behavioral studies with children learning English and children learning Japanese as their only language. The children range in age from 18 months to 4 years old. This research contributes to our understanding of the role of language in cognitive development and in so doing has direct implications for child health in the areas of language delay, environmental retardation, and other areas in which language learning is in some way compromised. In addition, the research seeks a fine grained specification of the learning mechanisms involved which have general significance beyond the role of language in early cognitive development. [unreadable] [unreadable]